s6o A L E M 
the augmentation of his means only by increaiing difplays 
of his beneficence, concealing his growing reputation and 
celebrity from thefe honelf people, and making their plain 
and uncouth manners tire fubjeft of good-natured plea- 
iantry and philofophical obfervation. His good nurfie 
perceived his ardent activity ; heard him mentioned as the 
writer of many books; but never took it into her head 
that he was a great man, and rather beheld Him with a 
kind of companion. “ You will never (faid flie to him 
one day) be any thing but a philofopher—and what is a 
philofopher ?—a fool, who toils and plagues himfelf all 
liis life, that people may talk of him when he is dead.” 
As d’Alembert’s fortune did not far exceed the demands 
of neceffity, his friends advifed him to think of fome pro- 
felfion that might enable him to encreafe it. He accord¬ 
ingly turned his views to the law, and took his degrees in 
that faculty; but foon after, abandoning this line, he ap¬ 
plied himfelf to the ftudy of medicine. Geometry how¬ 
ever was always drawing him back to his former purluits, 
lb that, after many ineffectual druggies to refid its attrac¬ 
tions, he renounced all views of a lucrative profeflion, and 
gave himfelf up entirely to mathematics and poverty. 
In the year 1741 he was admitted a member of the 
Academy of Sciences; for which diftinguifhed literary 
promotion, at fo early an age as twenty-four, he had pre¬ 
pared the way by correfting the errors of a celebrated 
work (the Analyfe Demontree of Reyneau), which was 
edeemed cladical in France in the line of analytics. He 
afterwards fet himfelf to examine with clofe attention and 
adiduity, what mud be the motion and path of a body, 
which paffes from one fluid into another denfer fluid, in a 
direction oblique to the furface between the two fluids. 
Every one knows the phenomenon which happens in this 
cafe, and amufes children, under the denomination of 
ducks and drakes ; but it was d’Alembert who firfl explain¬ 
ed it.in a fatisfadtory and philofophical manner. 
Two years after his election to a place in the academy, 
he publifhed his Treatife on Dynamics. The new princi¬ 
ple developed in this treatil'e, confided in edablilhing an 
equality, at each inflant, between the changes that the 
motion of a body has undergone, and the forces or pow¬ 
ers which have been employed to produce them; or, to 
exprefs the fame thing otherwife, in feparating into two 
parts the adtion of the moving powers, and confidering the 
ene as producing alone the motion of the body in-the fe- 
cond inflant, and the other as employed to defiroy that 
which it had in the firfl. 
So early as the year 1744, d’Alembert had applied this 
principle to the theory of the equilibrium, and the motion 
of fluids; and all the problems before refolved in phy- 
fics became in fome meafure its corollaries. The difco- 
very of this new principle was followed by that of a new 
calculus, the firfl effiiys of which were publifhed in a Dif- 
courfe on the General Theory of the Winds, to which the 
prize-medal was adjudged by the Academy of Berlin in 
the year 1746, which proved a new and brilliant addition 
to the fame of d’Alembert. This new calculus of Partial 
Differences he applied, the year following, to the problem 
of vibrating chords, the refolution of which, as well as 
the theory of the ofcillations of the air and the propaga¬ 
tion of found, had been but imperfectly given by the 
mathematicians who preceded him; and thefe were his 
mafters or his rivals. 
In the year 1749 he furnifhed a method of applying his 
principle to the motion of any body of a given figure. 
He alio refolved the problem qf the preceflion of the 
equinoxes; determining its quantity, and explaining the 
phenomenon of the nutation of the terreflrial axis difco- 
vered by Dr. Bradley. 
In 1752, d’Alembert publifhed a Treatife on the Refift- 
ance of Fluids, to which he gave the modeft title of an 
ejay; though it contains a multitude of original ideas and 
new obfervations. About the fame time lie publifhed, in 
the Memoirs of the Academy of Berlin, Refearches con¬ 
cerning the Integral Calculus, which is greatly indebted 
BERT. 
to him for the rapid progrefs it has made in the prefent 
century. 
While the ftudies of d’Alembert were confined to mere 
mathematics, he was little known or celebrated in his na¬ 
tive country. His connections were limited to a f'mall fo- 
ciety of feleCt friends. But his chearful converfation, 
his fmart and lively (allies, a happy knack at telling a (lo¬ 
ry, a lingular mixture of malice of fpeech with goodnefs 
of heart, and of delicacy of wit with fimplicity of man¬ 
ners, rendering him a pleafing and interefling companion, 
his company began to be much fought after in the fafhion- 
able circles. His reputation at length made its way to the 
throne, and rendered him the objeCt of royal attention 
and beneficence. The confequence was a penfion from 
government, which he owed to the friendfhip of count 
d’Argenfon. 
But the tranquillity of d’Alembert was abated when 
his fame grew more extenfive, and when it was known be¬ 
yond the circle of his friends, that a fine and enlightened 
tafte for literature and philofophy accompanied his ma¬ 
thematical genius. Our author’s eulogid afcribes to envy, 
detraction, &c. all the oppofition and cenftire that d’Alem¬ 
bert met with on account of the famous Encyclopedic, or 
Dictionary of Arts and Sciences, in conjunction with Di¬ 
derot. None furely will refitfe the well-deferved tribute 
of applaufe to the eminent difplays of genius, judgment, 
and true literary tafte, with which d’Alembert has enrich¬ 
ed that great work. Among others, the preliminary dif- 
courfe he has prefixed to it, concerning the rite, progrefs, 
connections, and affinities, of all the branches of human 
knowledge, is perhaps one of the moft capital productions 
the philofophy of the age can boatt of. 
Some time after this, d’Alembert publiflied his Philo¬ 
fophical, Hiftorical, and Philological, Mifcellanies. Thefe 
were followed by the Memoirs of Chriftina queen of 
Sweden ; in which d’Alembert ftiewed that he was ac¬ 
quainted with the natural rights of mankind, and was bold 
enough to aflert them. His Eflay on the Intercourfe of 
Men of Letters, with Perfons high in Rank and Office, 
wounded the former to the quick, as it expofed to the eyes 
of the public the ignominy of thofe fervile chains, which 
they feared to (hake oft', or were proud to wear. A lady 
of the court hearing one dav the author accufed of hav¬ 
ing exaggerated the defpotifm of the great, and the fub- 
million they require, anlwered llily, “If he had confult- 
ed me, I would have told him ftill more of the matter.” 
D’Alembert gave elegant fpecimens of his literary abi¬ 
lities in his tranflations of fome feledt pieces of Tacitus. 
But thefe occupations did not divert him from his mathe¬ 
matical ftudies; for about the fame time he enriched the 
Encyclopedic with a multitude of excellent articles in, 
that line, and compofed his Refearches on feveral Impor¬ 
tant Points of the Syftem of the World, in which he car¬ 
ried to a higher degree of perfection the folution of the 
problem concerning the perturbations of the planets, that 
had feveral years before been prefented to the academy. 
In 1759 he publiflied his Elements of Philofophy: a work 
much extolled as remarkable for its precifion and perfpi- 
cuity. 
The refentment that was kindled (and the difputes that 
followed it) by the article Geneva, inferted in the Ency¬ 
clopedic, are well known. D’Alembert did not leave' 
this field of controverfy with flying colours. Voltaire 
was an auxiliary in the conteft; but as he had no reputa¬ 
tion to lol’e, in point of candour and decency ; and as he 
weakened the blows of his enemies, by throwing both 
them and the fpedtators into fits of laughter ; the ifliie of 
the war gave him little uneafinefs. It fell more heavily on 
d’Alembert; and expofed him, even at home, to much* 
contradiction and oppofition. 
It was on this occalion that the late king of Pruffia of¬ 
fered him an honourable afylum at his court, and the- 
office of prefident of his academy; and the king was not 
offended at d’Alembert’s refufal of thefe diftindtions, but 
cultivated an intimate friendfhip with him during the reft 
of 
